1. Field of the Invention
This invention relates to a method of processing a radiation image in a radiation image recording system used for medical diagnosis and an apparatus therefor. This invention particularly relates to an image processing method and apparatus in a radiation image recording system in which a stimulable phosphor is used for recording radiation image information as an intermediate recording medium and the image recorded therein is read out for reproduction and finally recorded on a recording medium.
2. Description of the Prior Art
It is known in the art as disclosed in U.S. Pat. No. 3,859,527 to record radiation image information in a stimulable phosphor by exposing the phosphor to radiation transmitted through an object such as a human body, then reading out the recorded information by use of a photodetector by stimulating the phosphor with a scanning laser beam or the like, and record recording the read out information on a recording medium by modulating a recording laser beam or the like with the information read out by the photodetector.
The above-described radiation image recording system is far more advantageous than the conventional radiography system using a silver halide photographic film in that the image is recorded over a very wide range of radiation exposure. Therefore, this system is particularly useful when applied in medical diagnosis in which the human body is recorded in the same manner as in conventional radiography. By using this system for such purposes, it becomes possible to obtain information which cannot be obtained with conventional radiography because of the limited exposure range that can be recorded and observed on the conventional X-ray film.
Further, since the X-rays do harm to the human body, it is impossible from the viewpoint of safety to expose the human body to X-rays of high dose. Therefore, it is desired that the necessary information for radiography be obtained by exposing the human body only once to X-rays of a comparatively low dose. On the other hand, radiographs should preferably have both wide exposure latitude and high image quality including high contrast, high sharpness, low noise etc. for viewing and diagnosis. Unfortunately, since the conventional radiography system is designed so as to satisfy all the required conditions to some extent, the range of recording density or the ability to record various levels of information and the image quality are both insufficient and neither of these properties are completely satisfied.
The radiation image recording system as mentioned hereinbefore disclosed in U.S. Pat. No. 3,859,527 thus does not solve the above problems of conventional radiography.